Conversion of hydrocarbon oils



May 4, 1937. J. B. HElD CONVERSION 0F HYDROCARBON OILS Filed June 7,1934 (oke fila??? M, m, m4@

`30 resulting vaporous and liquid PatentedMay 4,VA 1937Y UNITED STATESPATENT ortis 2,079,168 CONVERSION OF HYDROCARBON OILS Jacob BenjaminHeid, Chicago,

Ill., assigner to Universal Oil Products Company, Chicago, Ill., acorporation of Delaware Y This invention particularly refers to amimproved process for the pyrolytic conversion of hydrocarbon oilsaccompanied by reduction of the residualliquid conversion products tocoke.

. More specifically the invention embodies a selective crackingoperation wherein hydrocarbon oil charging stock for the process,preferably of a relatively high-boiling nature, and selected low-boilingfractions of the reflux condensate (intermediate products recovered byfractionation of the vaporous conversion products) are subjected toindependently controlled conversion conditions and wherein residualliquid resulting from conversion of the charging stock is subjected tocoling and high-boiling fractions of the reflux condensate subjected tofurther conversion without being passed through a heating coil; thehighly heated products resulting from conversion of the selectedlow-boiling fractions of the reflux condensate serving as a heat`carrying medium for coking of the residue and conversion of thehigh-boiling fractions of the reflux condensate.

In one specific embodiment, the invention comprises subjecting ahydrocarbon oil charging stock of relatively high-boilingcharacteristics to conversion conditions of elevated temperature andsuperatmospheric pressure in a heating coil and communicating reactionchamber, separating the conversion products, subjecting the vapors tofractionation `whereby 'their insumciently converted components arecondensed as reflux condensate, subjecting fractionated vapors of thedesired end boiling point to condensation, recovering the resultingdistillate, separating the reflux condensate into selected relativelylow-boiling and highboiling fractions, subjecting the low-boiling frac-Ytions to independently controlled conversion con- 40 ditions ofelevated temperature and superatmospheric pressure in a separate heatingcoil, intro- I ducing the4 resulting products into a coking chamber,commingling the aforementioned residual liquid and the high-boilingfractions of the reflux condensate with the `heated products suppliedfrom said separate heating coil to the coking chamber, for the purposeof effecting further `conversion of the high-boiling reflux condensateand reducing the residue to coke, and subjecting vaporous products fromthe coking zone to said fractionation.

The featuresv of the present invention and their advantages will be moreapparent with reference to the accompanying diagrammatic drawingand thefollowing descriptionthereof.

in chamber The drawing illustrates one specific form of apparatus inwhich the process of the present invention maybe accomplished.

Referring to the drawing, hydrocarbon Voil charging stock for ,theprocess, which may be any desired type of oil but preferably comprisesan oil ofrelatively high-boiling characteristics such as, for example,crude petroleum, topped crude, fuel oil, gas oil and, in general, heavydistillates and residual oils may be supplied through line l and valve 2to pump 3 wherefrom it may be directed through line 4 and valve 5 toheating coil 6. The charging stock may, of course, be preheated in anysuitable well known manner, not illustrated, prior to its introductioninto the heating coil such as, for example, by indirect contact and heatexchange with hot vaporous and/or liquid products of the process.

A furnace' 'l of any suitable form supplies the required heat to the oilpassing through heating coil 6 to bring it to the desired temperature,preferably at a substantial superatmospheric pressure, and the stream ofheated oil is discharged fromthe heating coil through line 8 and valve 9into reaction chamber I0.

Chamber I0 is also preferably maintained at a substantialsuperatmospheric pressure, which may be the same n orrsomewhat lower'than that vemployed at the outlet from the heating coil and,

although not indicated in the drawing, the reaction chamber ispreferably insulated to prevent the excessive loss of heat so thatconversion of the heated products supplied to this Zone from heatingcoil 6 may continue therein. Separation of vaporous and residual ucts isaccomplished, in the case here illustrated, l0. The residual liquid iswithdrawn from the lower portion of this zone through line II and valveI2 and is subjected to coking, as will be laterA more fully described,while the vaporous conversion products pass from the upper portion ofthe reaction chamber through line I3 and valve lll toffractionation infractionator l5.

The vaporous products from the coking operation are also'supplied tofractionator l5, in the case here illustrated, as will be later morefully described, and the components of the total vaporous productssupplied to this zone boiling above the range of the desired final lightdistillate prodp uct of the process are condensed as reflux condensate.Fractionated vapors of the desired endboiling point are withdrawn,together with uncondensable gas produced by the operation, from theupper portion of fractionator l5 through line I6 and valve I'l and aresubjected to condensaliquid conversion prod- 3 tion and cooling incondenser I8. The resulting distillate and gas passes through line I9and valve 20 to collection and separation in receiver 2I. Uncondensablegas may be released from the receiver through line 22 and valve 23. Thedistillate may be withdrawn from receiver 2 I through line 24 and valve25 to storage or to any desired further treatment. When desired, aregulated portion of the distillate collected in receiver 2I may berecirculated, by Well known means, not

shown in the drawing, to the upper portion of fractionator I5 to serveas a reuxing and cooling medium to assist fractionation of the vaporsand maintain the desired vapor outlet temperature from the fractionator.

The reflux condensate formed in fractionator I5 is separated intoselected relatively low-boiling and high-boiling fractions. The `formermay be withdrawn from any suitable intermediate point or plurality ofpoints in the fractionatorr passing, for example, through line 26 andvalve `2I tozpump 28 by means of which they .are supplied through line29 and valve 30 to furtherconversion in heating coil 3l.

Heating coil 3| is located in a furnace 32 of any suitable form bymeans-of which the oil supplied to the heating coil is brought to thedesired conversion temperature, preferably at a substantialsuperatmospheric pressure. Preferably the relatively low-boiling oilsupplied to heating lcoil 3l is subjected therein to more severeconversion conditions than the charging stock supplied to heating coil5. The highly heated products from heating coil 3| aredischarged-therefrom through line 33 and valve 34 and are introducedinto coking chamber 35, entering this zone at any desired point orplurality of points such as, for example, through valve 36 in line 33into the lower yportion of the coking chamber or from -line 33 throughline 31, valve 38, line 39 and valve 40 into the upper portion of thechamber.

High-boiling fractions of the reuxcondensate recovered in fractionatorI5 may be withdrawn from the lower portion of this zone through line 4Iand valve 42 to pump 43 by means of which they may be directed throughline 44 and valve 45 into line 41, commingling therein with residualliquid withdrawn from chamber I0, as previously described, through lineII and valve I2 to pump 46 wherefrom it is discharged through line -41and valve 48. The stream of commingled residual liquid and high-boilingreflux condensate may then be directed into coking chamber 35, enteringthis zone Yat any desired point or plurality of points, either alone ortogether lwith the stream of highly heated products supplied to "thiszone from heating coil 3|. The drawing indicates provision for supplyingthe commingled residual liquid and high-boiling reflux condensate tocoking chamber 35 through ,line l39 and valve 40 or through line''l,valve 38, line 33 and valve 36. It is also within the scope of theinvention to .commingle either the stream of residual liquid fromchamber Ill nr the stream -of high-*boiling reflux condensate fromfractionator I5 with the stream of highly heated products passing :from:heating coil 3l into cokingfchamber ..35 :and to supply Vthe otherstream `direct to Athe coking :chamber :at vany desired point, although:means 'for accomplishing this are not illustratedin the'drawing.Whenth'e stream of residual liquid or the streamof .highboiling refluxcondensate, or both, `are commingled Ywith the stream of iheatedproductsfrom heating Vcoil 3| in line .'33 `they serve to reduce thevtemperature of the `conversion products and retard their furtherconversion, prior to their introduction into the coking chamber and, inany case, regardless of the method employed for supplying the variousmaterials to the coking chamber, the products from heating coil 3I serveas a heat carrying medium to effect further conversion of thehigh-boiling reux condensate from fractionator I5 and to effectreduction of the residual materials in chamber 35 to coke.

The coke formed in chamber 35 may be allowed to accumulate in this zoneto be removed therefrom, in any suitable manner not illustrated,

after the voperation Aof the chamber is completed and, when desired, aplurality of coking chambers similar to chamber 35, but not illustrated,may be employed and may be simultaneously opy'erated or, preferably, arealternately operated,

cleaned and `prepared for further operation so that the coking stage ofthe process as well as the cracking stages may be continuous. Chamber 35lis provided lwith a suitable drain-line 49, controlled by valve 50which may lalso serveas means for introducing steam, water or any otherysuitable cooling medium into -chamber 35, after its .operation has beencompleted and it has been isolated from the rest of the system, in orderto hasten cooling and facilitate lcleaning of the chamber. Vaporousproducts vare directed from the coking chamber through line 5I, valve 52and line I3 vto fractionation in fractionator I5, to-

gether with the vaporous conversion products from chamber IIJ. Itis,however,entire1y Within the scope of the present invention, whendesired, to separately fractionate the vaporous products from chambersI0 and 35, although .means for rf accomplishing this are notillustrated.

In an apparatus such as illustrated and above described, the preferredrange of operating conditions may be approximately as follows: Thecharging stock may be subjected in the heating coil to which it issupplied, to an outlet conversion temperature ranging, for example, from800 to 950 F., or thereabouts, preferably with a superatmosphericpressure at this point in the system of from 100 to 500 pounds, orthereabouts, per sq. in. The reaction chamber following the chargingstock heating coil may employ substantially the same or somewhat lowerSuperatmospheric pressure than that employed at the outlet from theheating coil. Conversion conditions more severe than those employed forthe charging stock are preferably utilized for conversion of thelow-boiling fractions of the reflux condensate, the outlet conversiontemperature from the heating coil to which the light reflux condensateis supplied ranging, forexample, from 925 to 1050 F., or thereabouts,preferably with a superatmospheric pressure, measured at the outlet fromthe heating coil, of from 200 to 800 pounds, or more, per sq. in. 'I'hecoking chamber may be operated at any desired pressure ranging fromsubstantially atmospheric up to the pressure employed at the outlet fromthe light reflux heating coil and may be varied to suit requirements,depending upon the characteristics of the coke desired and upon thenature of the high-boiling reflux condensate supplied to this zone andthe degree of conversion to which it is desired to subject the same. Thefractionating, condensing and collecting portions of the system mayemploy pressures substantially the same or somewhat lower than thepressure employed in the coking chamber.

As a specific example of the operation of the process of the presentinvention as it may be practiced in an apparatus of the characterillustrated and above described; the charging stock, comprising aMid-Continent topped crude of about 25 A. P. I. gravity, is subjected toa conversion temperature, measured at the outlet from the heating coilto which it is supplied, of approximately 900 F. at a superatmosphericpressure of about 275 pounds per sq. in. Substantially lthe samepressure is employed in the succeeding reaction chamber. LoW-boilingfractions of the reflux condensate resulting from fractionation of thevaporous products of the process, which fractions boil belowapproximately 650 F., are subjected in a separate heating coil to anoutlet conversion temperature of approximately 950 F. at asuperatmospheric pressure of about 400 pounds per sq. in. The stream ofheated products from the light oil heating coil is commingled withresidual liquid withdrawn from the reaction chamber and the remaininghigher boiling fractions of the reflux condensate, the commingledmaterials being introduced into a coking chamber which is operated at asuperatmospheric pressure of about 150 pounds per sq. in. This operationwill produce, per barrel of charging stock, about percent of goodquality motor fuel and about pounds of petroleum coke having a volatilecontent of approximately 7 percent and of substantially uniform qualityand good structural strength; the remainder being chargeable,principally, to uncondensable gas.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oils whereinhydrocarbon oil charging stock for the process is subjected toconversion conditions of elevated temperature and superatmosphericpressure in a heating coil and communicating reaction chamber, theresulting vaporous conversion products and the residual liquidseparated, the vapors subjected to fractionation, whereby theirinsufficiently converted components are condensed as reflux condensate,fractionated vapors of the desired end-boiling point subjected tocondensation and the resulting distillate recovered, the improvementwhich comprises separating the reflux condensate into selectedrelatively low-boiling and high-boiling fractions, subjecting thelow-boiling fractions to independently controlled conversion conditionsof elevated temperature and superatmospheric pressure in a separateheating coil, introducing the resulting products into a coking chamber,commingling said residual liquid and said high-boiling fractions of thereflux condensate with the heated products from said separate heatingcoil supplied to the coking chamber, the high boilized oil in aseparating zone, fractionating the vapors to separate a relatively heavyreflux condensate and a lighter reflux condensate therefrom, passing thelighter reflux condensate through a second heating zone and heating thesame therein to higher cracking temperature n than the oil in thefirst-named heating zone, removing said unvaporized oil from theseparating zone and introducing the same to a reduced pressure cokingzone, also introducing said heavy reflux condensate, without priorsubstantial cracking thereof, into the coking zone, discharging heatedproducts from the second heating zone into the coking zone and thereindistilling the unvaporized oil and heavy reflux condensate to coke bythe heat of said products, combining vapors thus formed in the cokingzone with the first-named vapors for fractionation in admixture with thelatter, and finally condensing the fractionated vapors.

JACOB BENJAMIN HEID.

